cake                  package:lme4                  R Documentation

_B_r_e_a_k_a_g_e _a_n_g_l_e _o_f _c_h_o_c_o_l_a_t_e _c_a_k_e_s

_D_e_s_c_r_i_p_t_i_o_n:

     Data on the breakage angle of chocolate cakes made with different
     recipes and baked at different temperatures.

_U_s_a_g_e:

     data(cake)

_F_o_r_m_a_t:

     A data frame with 270 observations on the following 5 variables.

     '_r_e_p_l_i_c_a_t_e' a factor with levels '1' to '15'

     '_b_a_t_c_h' a factor with levels '1', '2' and '3'

     '_r_e_c_i_p_e' a factor with levels '1', '2' and '3'

     '_t_e_m_p_e_r_a_t_u_r_e' an ordered factor with levels '175' < '185' < '195'
          < '205' < '215' < '225'

     '_a_n_g_l_e' a numeric vector giving the angle at which the cake broke.

_D_e_t_a_i_l_s:

     The 'replicate' factor is nested within the 'branch' factor.

_S_o_u_r_c_e:

     Original data given in Cochran and Cox (1957).

_R_e_f_e_r_e_n_c_e_s:

     Also cited in Lee, Nelder and Pawitan (2006)

_E_x_a_m_p_l_e_s:

     str(cake)
     print(fm1 <- lmer(angle ~ recipe * temperature + (1|replicate/batch), cake,
                  method = "ML"), corr = FALSE)
     print(fm2 <- lmer(angle ~ recipe + temperature + (1|replicate/batch), cake,
                  method = "ML"), corr = FALSE)
     print(fm3 <- lmer(angle ~ recipe + as.numeric(temperature) +
                  (1|replicate/batch), cake, method = "ML"), corr = FALSE)
     anova(fm3, fm2, fm1)

